The purpose of this project is to determine the etiology of the autoimmune disease Sjogren's Syndrome. Particularly we studied the basis of clinical, serologic and genetic similarities and differences between Sjogren's syndrome alone and Sjogren's syndrome associated with other autoimmune disease; the presence and physiochemical properties of immune complexes in the patients, the ability of the Fc receptor of their RES to clear immune complexes, and the immunoregulation of primary Sjogren's syndrome.